Interleukin-6 (IL-6) is involved in several diseases, including many cancers and autoimmune diseases. Interleukin-6 is secreted by many advanced cancers, such as hormone-independent prostate cancer, and is believed to be a growth factor for such cancers. In addition, the secretion of IL-6 by cancer cells is believed to cause cachexia, the wasting syndrome characteristic of advanced cancers. Therefore, inhibition of IL-6 action would be useful in treatment of such cancers.
IL-6 also plays a key role in B cell development. Autoimmune diseases with a significant antibody component, such as rheumatoid arthritis, could be treated by inhibition of IL-6. Disorders involving proliferation of B cells, such as multiple myeloma and B cell lymphoma, could also be treated by inhibition of IL-6 activity.
In addition, IL-6 plays an important role in bone remodeling by promoting bone resorption. Inhibitors of IL-6 activity would have the effect of reducing bone resorption and could be used to treat osteoporosis.
When IL-6 is produced as part of a disease or disorder, it is often complexed with a soluble IL-6Ralpha subunit and is often secreted from cells in the form of such a complex. As a result, it is often not useful to treat a patient with an antibody or other inhibitor that blocks the interaction between IL-6 and IL-6Ralpha, because such an antibody or inhibitor can have no effect on a pre-formed complex. Therefore, there is a need in the art for improved treatment of IL-6-mediated diseases.